Coronary heart disease (CHD) remains the leading cause of death in the industrialized countries. The primary cause of CHD is atherosclerosis, a disease characterized by the deposition of lipids, including cholesterol, in the arterial vessel wall, resulting in a narrowing of the vessel passages and ultimately hardening of the vascular system. Epidemiological studies have demonstrated an inverse relationship between serum high density lipoprotein cholesterol (HDLc) levels and the incidence of CHD (Castelli, W. P. et al., J. Am. Med. Assoc., 256, 2835 (1986); Miller and Miller Lancet, 1, 16 (1975); Gordon et al., Circulation 79, 8 (1989)). Low levels of HDLc represent a significant independent CHD risk factor whether or not these patients have elevated low density lipoprotein cholesterol (LDLc) levels (Kannel, W. B., Am. J. Cardiol. 76, 69c (1995)). Indeed, high density lipoprotein (HDL) is recognized as the anti-atherogenic lipoprotein (Stein, O. and Stein, Y., Atherosclerosis 144, 28 (1999)). Several clinical studies have demonstrated reduced CHD events with treatments that raised HDLc. For example, the recent VA-HIT trial showed for the first time that by raising HDL cholesterol without affecting LDL cholesterol, cardiac events in patients with CHD were substantially reduced (Rubins, H. B. and Robins, S., Am. J. Cardiol. 86, 543 (2000)). Every 1% rise in HDLc, produced a corresponding 2-3% decrease in CHD.
Atherosclerosis generally begins with local injury to the arterial endothelium followed by proliferation of arterial smooth muscle cells from the medial layer to the intimal layer along with the deposition of lipid and accumulation of foam cells in the lesion. As the atherosclerotic plaque develops it progressively occludes more and more of the affected blood vessel and can eventually lead to ischaemia or infarction. Because deposition of circulating lipids such as cholesterol plays a major role in the initiation and progression of atherosclerosis, it is important to identify compounds, methods and compositions to help remove cholesterol from the developing peripheral tissues, including atherosclerotic plaque. As described below, HDL promotes reverse cholesterol transport, a process by which excess cholesterol is extracted from peripheral cells by HDL and delivered to the liver for its elimination. Thus, it is important to identify compounds, methods and compositions that can increase HDLc (Euro. Heart J. 2001 March 15; 22(6), 465-471) and improve the functionality of HDL (K. Alam et al., J. Biol. Chem. 2001, in press).
Circulating lipoproteins serve as vehicles for the transport of water-insoluble lipids like cholesteryl esters, triglycerides and the more polar phospholipids and unesterified cholesterol in the aqueous environment of plasma (Bradely, W. A. and Gotto, A. M.: American Physiological Society, Bethesda, Md., pp 117-137 (1978)). The solubility of these lipids is achieved through physical association with proteins termed apolipoproteins, and the lipid-protein complexes are called lipoproteins (Dolphin, P. J., Can. J Biochem. Cell. Biol. 63, 850-869 (1985)). Five distinct classes of lipoproteins have been isolated from human plasma: chylomicrons, very low density lipoproteins (VLDL), low density lipoproteins (LDL), high density lipoproteins (HDL) and lipoprotein) (a (LP(a)). (Alaupovic, P. (1980) In Handbook of Electrophoresis. Vol. 1, pp. 27-46; Havel, R. J., Eder, H. A.; Bragdon, J. H., J. Clin. Invest. 34, 1343 (1955)).
HDL particles are first secreted from the liver and intestine as small, discoidal particles called “pre-beta 1” HDL. HDL particles undergo a continuous interconversion in the plasma beginning with the conversion of the “nascent discoidal “pre-beta 1” HDL into spherical HDL3, through the action of plasmatic enzymes, mainly lecithin-cholesteryl acyltransferase (LCAT), that converts free cholesterol to cholesteryl ester (Glomset J. A., and Norum K. R., Advan. Lipid Res., 11, 1-65, (1973)); McCall, M. R., Nichols, A. V., Morton, R. E., Blanche, P. J., Shore, V. G., Hara, S. and Forte, T. M., J. Lipid Res. 34, 37 (1993)). HDL3 acquires phospholipids (PL) and free cholesterol (FC) in the presence of other plasmatic enzymes such as lipoprotein lipase (LPL) (Patsch, J. R., Gotto, A. M., Olivercrona, T. and Eisenberg, S., Proc. Natl. Acad. Sci., 75, 4519 (1978)), and further action of LCAT helps form large CE-rich HDL which constitute the CE-rich HDL2 subpopulation (McCall, M. R., et al., J. Lipid Res. 34, 37 (1993)). Mature HDL is spherical and contains various amounts of lipids and apolipoprotein. Apolipoprotein A-I (apoAI) is the major protein component of mature HDL, and most of the cholesterol associated with HDL is esterified as cholesteryl esters (CE). HDL is believed to play a fundamental functional role in the transport of lipids and represents a site for storage of potentially harmful lipids and apolipoproteins which if unregulated could have harmful effects including changing cellular functions, altering gene expression, and obstructing blood flow by narrowing the vessel lumen. apoAI has been found to be more powerful as a marker for coronary disease than the cholesterol component of HDL (Maciejko J. J. et al., New England J. Med. 309, 385-389 (1983)). However, HDLc remains an important independent predictor of atherosclerosis, and HDLc is an important predictor of survival in post coronary artery bypass graft patients as a result of the 20-year experience from The Cleveland Clinic Foundation ((Foody J M et al. (2000) Circulation, 102 (19 suppl3), III90-94). Clinical surveys have confirmed that elevated HDLc is favorable in preventing the development of atherosclerotic lesion and low levels of HDLc together with low apoAI levels are currently considered to be the most reliable parameters in predicting the development of atherosclerosis in hyperlipidemic patients ((Mingpeng s and Zongli W, (1999) Experimental Gerontology, 34 (4); 539-48)).
Reverse Cholesterol Transport
HDL promotes reverse cholesterol transport, a process by which excess cholesterol is extracted from peripheral cells by HDL and delivered to the liver for its elimination. Reverse cholesterol transport, therefore, reduces cholesterol accumulation in the artery wall (Reichl, D and Miller, N. E., Arteriosclerosis 9, 785 (1989)). Because there is no cholesterol accumulation in extrahepatic organs, cholesterol must be transported to the liver by HDL for ultimate excretion into bile, either as free cholesterol, or as bile acids that are formed from cholesterol (Kwiterovich, P. O., Amer. J. Cardiol. 82, 13Q, (1998)). HDL may acquire part of its anti-atherogenic character by promoting the reverse transport of cholesterol. Because promoting the reverse transport of cholesterol leads to removal of cholesteryl esters and antiatherogenic effects, it is important to discover new compounds that promote the reverse transport process. One potential target for promoting reverse transport is apoAI, because increased apoAI would allow more efflux of cholesterol from peripheral tissues, including atherosclerotic lesions, and also improve the functionality of circulating HDL. The major functional role of HDL is to remove cholesterol from peripheral tissues including atherosclerotic lesions and taking cholesterol in its ester form to the liver for elimination. It would therefore be desirable to improve the functionality of HDL by acting on proteins and receptors involved in RCT in such a way as to increase the half life of apoAI-HDL and/or to increase the delivery of cholesteryl esters to the liver.
Reverse cholesterol transport involves several steps that are important for the transport of cholesterol from artery walls and in general from peripheral cells to the liver. The first step is the efflux of cholesterol from peripheral tissues to nascent and circulating HDL particles (Fielding C. J. and Fielding P. E, J. Lipid. Res. 36, 211 (1995); Rothblat G. H., de la Llera-Moya, M., Atger, V., Kellner-Weibel, G., Williams, D. L., and Phillips, M. C., J. Lipid Res. 40, 781 (1999)). Recent findings suggest that ABC1 (ATP-cassette binding protein 1) plays a crucial role in that process (Gura, T., Science 285, 814 (1999)). The second step involves the plasmatic modulation of HDL that loads cholesterol from peripheral cells, and the interactions with plasmatic enzymes and proteins that modulate plasma HDL concentrations during this process. One major enzyme known as lecithin-cholesteryl acyltransferase (LCAT) and its cofactor apoAI promote the esterification of free cholesterol to cholesteryl ester, which is then packaged into the core of the HDL (Kwiterovich, P. O., Amer. J. Cardiol. 82, 13Q (1998)). LCAT function maintains a concentration gradient (Francone et al., J. Biol. Chem. 264, 7066 (1989)). Cholesteryl ester transfer protein (CETP) helps shuttle excess cholesteryl ester from HDL to triglyceride-rich lipoproteins in exchange for triglycerides (Eisenberg, J. Lipid Res. 26, 487 (1985); Morton, R. E., and Zilversmit D. B., J. Biol. Chem., 258, 11751 (1983)). The last step of the reverse cholesterol transport involves the movement of cholesterol in its esterified form from HDL to the liver and from there into the bile, either directly or after conversion to bile acids, for ultimate elimination.
Numerous efforts are being made to understand the process of reverse cholesterol transport and the underlying mechanisms of cholesterol and cholesteryl ester exchange between cellular surfaces and HDL. The cholesteryl esters at the core of the HDL may be delivered to the liver for elimination by several mechanisms. First, the receptor independent model explains diffusion as a process for both the uptake and the eflux of free cholesterol (Rothblat, G. H. et al., J. Lipid Res., 40, 781 (1999)). Second, cholesteryl ester transfer protein moves cholesteryl ester from HDL to the triglyceride rich lipoproteins and very low density lipoprotein. The cholesteryl esters are then taken up by the liver through the LDL receptor pathway. Third, if the cholesteryl ester transfer protein activity is low, large apolipoprotein-E containing HDL particles may be cleared via the LDL receptor pathway. Fourth, cholesteryl ester may be selectively removed from HDL by an HDL receptor on the liver (Kwiterovich, P. O., Amer. J. Cardiol. 82, 13Q (1998); Arbeeny, C. M. et al., Biochem. Biophys. Acta. 917, 9 (1987)).
The receptor-dependent model accounts for HDL-binding proteins, such as class B, type I and type II scavenger receptors (SR-BI and SR-BII) which can mediate the selective uptake of HDL cholesteryl esters to the liver and steroidogenic tissues (Acton, S. et al., Science 271, 518 (1996); Murao, K. et al., J. Biol. Chem. 272, 17551 (1997); Webb, N. R. et al., J. Biol. Chem. 273, 15241 (1998)). It has been postulated that HDL binds to SR-BI at the cell surface via direct interaction between SR-BI and the amphipathic helical repeats of apolipoprotein A-I providing a water-depleted “channel” that allows cholesteryl ester (CE) molecules to diffuse from CE-rich HDL to the cell plasma membrane (Williams, D. L. et al., Current Opinion Lipidology, 10, 329 (1999); Rodrigueza W. V. et al., J. Biol. Chem. 274, 20344 (1999)). Mice with genetically manipulated SR-BI expression and the murine adrenal Y1-BS1 cell line have been useful in defining the role of SR-BI in HDL metabolism. HDL cholesterol levels are increased in animals deficient in SR-BI indicating the importance of SR-BI in the clearance of HDL cholesterol. However, activating the reverse cholesterol transport system through increased SRB-1 expression is a potential way to reduce atherogenesis if HDLc is not significantly reduced (Ueda, Y., Gong, E., Royer, L., Cooper, P. N., Francone, O. L., and Rubin E. M., J. Biol. Chem., 275, 27, 20368 (2000)). Therapeutic interference with HDL metabolism that will bring changes in the kinetics and functionality of HDL rather than plasma HDL cholesterol levels per se will reduce atherogenesis (Eckardstein, V., and Assmann, G., Current Opinion in Lipidology, 11, 627 (2000)). Therapeutic intervention that will increase HDL cholesterol and in addition improve HDL kinetics and functionality, will significantly reduce atherogenesis.
HDL catabolism by SR-B1 does not involve HDL holoprotein particle uptake and lysosomal degradation of apolipoproteins. This is supported by the finding that transgenic mice deficient in SR-B1 display elevated HDLc yet exhibit no change in levels of plasma apoAI (Rigotto, et al., Proc. Natl. Acad. Sci., 94, 12610 (1994)) Endocytosis and lysosomal degradation of HDL holoprotein is known to occur (Steinberg, D. Science, 274, 460 (1996)), but endocytic HDL receptors have remained elusive. A recently characterized receptor, cubilin, has been found to mediate HDL holoparticle endocytosis (Hammad et al., Proc. Natl. Acad. Sci., 96, 10158 (1999)). A similar protein or putative receptor, still remains to be found, that could be responsible for hepatic clearance of HDL holoproteins.
In humans, low HDL cholesterol levels may relate to defects in synthesis or catabolism of apoAI, with catabolic defects being more common (Brinton, E. A., et al., Ateriosclerosis Thromb. 14, 707 (1994)); Fridge, N., et al., Metabolism 29, 643 (1980)). Low HDL is often associated with hypertriglyceridemia, obesity, and insulin resistance (Brinton, E. A., et al., Ateriosclerosis Thromb. 14, 707 (1994)). HDL from hypertriglyceridemic subjects characterized by low HDL levels have small HDL particles which are susceptible to renal filtration and degradation. The liver is the principal organ of HDL apolipoprotein degradation (Horowitz, B. S., et al., J. Clin. Invest. 91, 1743 (1993)).
HDL has other important characteristics that may contribute to its anti-atherogenic properties. Recent evidence suggests that HDL may have antioxidant and antithrombotic properties (Tribble, D., et al., J. Lipid Res. 36, 2580 (1995); Mackness, M. I., et al., Biochem. J. 294, 829 (1993); Zeither, A. M., et al., Circulation 89, 2525 (1994)). HDL may also affect the production of some cell adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), (Cockerill, G. W., et al., Arterioscler. Thromb., 15, 1987 (1995)). These properties of HDL also provide protection against coronary artery disease.
Existing Lipid Therapies
Therapeutic agents that elevate HDL, are prime targets for drug development, given the evidence in favor of HDL and its protective function against atherosclerosis. Towards this end, one pathway targeted by industry has been to increase synthesis and secretion of apolipoprotein A-I (apoAI), the major protein in HDL.
U.S. Pat. No. 5,968,908 discloses analogs of 9-cis-retinoic acid and their use to raise HDLc levels by increasing the synthesis of apoAI.
U.S. Pat. No. 5,948,435 discloses a method of regulating cholesterol related genes and enzymes by administering lipid acceptors such as liposomes. Additionally, U.S. Pat. No. 5,746,223 discloses a method of forcing the reverse transport of cholesterol by administering liposomes.
Several known agents such as Gemfibrozil (Kashyap, A., Art. Thromb. Vasc. Biol. 16, 1052 (1996)) increase HDLc levels. Gemfibrozil is a member of an important class of drugs called fibrates that act on the liver. Fibrates are fibric acid derivatives (bezafibrate, fenofibrate, gemfibrozil and clofibrate) which profoundly lower plasma triglyceride levels and elevate HDLc (Sirtori C. R., and Franceschini G., Pharmac Ther. 37, 167 (1988); Grundy S. M., and Vega G. L. Amer. J Med. 83, 9 (1987)). The typical clinical use of fibrates is in patients with hypertriglyceridemia, low HDLc and combined hyperlipidemia.
The mechanism of action of fibrates is not completely understood but involves the induction of certain apolipoproteins and enzymes involved in VLDL and HDL metabolism. For example, cholesteryl ester transfer protein activity is reduced by fenofibrate, gemfibrozil, phentyoin and alcohol.
Ethanol is known to increase HDLc levels and has been found to decrease coronary disease risk (Klatsky, A. L., et al., Intern. Med. 117, 646 (1992)). Regular use of alcohol has been shown to be correlated with increases in serum apoAI and HDL cholesterol levels. These increases are believed to be related to liver cytochrome P450 induction (Lucoma, P. V., et al., Lancet 1, 47 (1984)).
Nicotinic acid (niacin), a water-soluble vitamin has a lipid lowering profile similar to fibrates and may target the liver. Niacin has been reported to increase apoAI by selectively decreasing hepatic removal of HDL apoAI, but niacin does not increase the selective hepatic uptake of cholesteryl esters (Jin, F. Y., et al., Arterioscler. Thromb. Vasc. Biol. 17, 2020 (1997)).
In addition, premenopausal women have significant cardio-protection as a result of high HDLc levels, probably due to estrogens. Tam et al. have shown that human hepatoma cells increased apoAI mass in culture medium when cells were treated with estrogen (Tam S. P., et al., J. Biol. Chem. 260, 1670 (1985); Jin, F. Y., et al., Arterioscler. Thomb. Vasc. Biol. 18, 999 (1998)). Dexamethasone, prednisone, and estrogen activate the apoAI gene, increase apoAI and HDL cholesterol, reduce lipoprotein B, and reduce LDL cholesterol (Kwiterovich, P. O. Amer. J. Cardiol. 82, 13Q (1998)). The side effects of such steroids are well known and limit their chronic use in atherosclerosis.
Diet contributes up to 40% of cholesterol that enters through the intestine and bile contributes the rest of the “exogenous” cholesterol absorbed through the intestine (Wilson M. D., and Rudel L. L. J. Lipid Res. 35, 943 (1994)). Decreasing dietary cholesterol absorption therefore is a regulatory point for cholesterol whole body homeostasis. Cholesterol absorption inhibitors lower plasma cholesterol by reducing the absorption of dietary cholesterol in the gut or by acting as bile acid sequestrants (Stedronsky, E. R., Biochim. Biophys. Acta 1210, 255 (1994)).
Cholesterol lowering agents decrease total plasma and LDL cholesterol and some may increase HDLc. Several such agents, which primarily reduce LDL cholesterol, are discussed because of an associated slight increase in HDLc levels. For example, statins represent a class of compounds that are inhibitors of HMG CoA reductase, a key enzyme in the cholesterol biosynthetic pathway (Endo, A., In: Cellular Metabolism of the Arterial Wall and Central Nervous System. Selected Aspects. Schettler G, Greten H, Habenicht A. J. R. (Eds.) Springer-Verlag, Heidelberg (1993)).
The statins decrease liver cholesterol biosynthesis, which increases the production of LDL receptors thereby decreasing total plasma and LDL cholesterol (Grundy, S. M. New Engl. J. Med. 319, 24 (1988); Endo, A., J. Lipid Res. 33, 1569 (1992)). Depending on the agent and the dose used, statins may decrease plasma triglyceride levels and some may increase HDLc. Currently the statins on the market are lovastatin (Merck), simvastatin (Merck), pravastatin (Sankyo and Squibb) and Fluvastatin (Sandoz). A fifth statin, atorvastatin (Parke-Davis/Pfizer), is the most recent entrant into the statin market. Statins have become the standard therapy for LDL cholesterol lowering. The statins are effective LDLc lowering agents but have some side effects, the most common being increases in serum enzymes (transaminases and creatinine kinase). In addition, these agents may also cause myopathy and rhabdomyolysis especially when combined with fibrates. Because of possible side effects of LDLc lowering drugs, it is important to discover novel compounds that possess antiatherogenic characteristics such as increasing HDLc levels and HDL functionality without raising LDLc levels.
Another drug that in part may impact the liver is probucol (Zimetbaum, P., et al., Clin. Pharmacol. 30, 3 (1990)). Probucol is used primarily to lower serum cholesterol levels in hypercholesterolemic patients and is commonly administered in the form of tablets available under the trademark Lorelco™. Probucol is chemically related to the widely used food additives 2,[3]-tert-butyl-4-hydroxyanisole (BHA) and 2,6-di-tert-butyl-4-methyl phenol (BHT). Its full chemical name is 4,4′-(isopropylidenedithio) bis(2,6-di-tert-butylphenol). Probucol is a lipid soluble agent used in the treatment of hypercholesterolemia including familial hypercholesterolemia (FH). Probucol reduces LDL cholesterol typically by 10% to 20%, but it also reduces HDLc by 20% to 30%. The drug has no effect on plasma triglycerides. The mechanism of action of probucol in lipid lowering is not completely understood. The LDLc lowering effect of probucol may be due to decreased production of apoB containing lipoproteins and increased clearance of LDL. Probucol lowers LDLc in the LDL-receptor deficient animal model (WHHL rabbits) as well as in FH populations. Probucol has been shown to actually slow the progression of atherosclerosis in LDL receptor-deficient rabbits as discussed in Carew et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84:7725-7729. The HDLc lowering effect of probucol may be due to decreased synthesis of HDL apolipoproteins and increased clearance of this lipoprotein. High doses of probucol are required in clinical use.
U.S. Pat. No. 6,004,936 to Robert Kisilevsky describes a method for potentiating the release and collection of cholesterol from inflammatory or atherosclerotic sites in vivo, the method including the steps of increasing the affinity of high-density lipoprotein for macrophages by administering to a patient an effective amount of a composition comprising a compound selected from the group consisting of native serum amyloid A (SAA) and a ligand having SAA properties thereby increasing the affinity of high density lipoprotein (HDL) for macrophages and potentiating release and collection of cholesterol.
U.S. Pat. Nos. 5,821,372 and 5,783,707 to Elokdah et al. describe 2-thioxo-imidazolidin-4-one derivatives that are useful for increasing blood serum HDL levels.
U.S. Pat. No. 6,171,849 to Rittersdorf et al. discloses an apparatus comprising a first porous carrier and a second porous carrier for evaluating biological fluid samples. The apparatus is used for separating non high density lipoprotein (non-HDL) from a lipoprotein in a body sample and for determining high density lipoprotein (HDL) cholesterol in a HDL and non high density lipoprotein (non-HDL) in a body sample.
European Patent Publication 1029928 A2 to Watanabe, Motokazu et al. discloses a method for determining cholesterol in low density lipoprotein comprising the steps of (a) measuring total cholesterol level in a sample containing at least high density lipoprotein, low density lipoprotein, very low density lipoprotein and chylomicron, and (b) measuring cholesterol levels in the high density lipoprotein, very low density lipoprotein and chylomicron in the sample, wherein the cholesterol level in the low density lipoprotein is determined by subtracting a value obtained in the step (b) from a value obtained in the step (a). The invention enables concurrent determination of cholesterol level in low density lipoprotein and total cholesterol level, facilitating acquisition of two types of biological information at a time.
International application WO 01/7388 A1 to Sugiuchi describes a method for fractional quantification of cholesterol in low density lipoproteins; a quantification reagent to be used; a method for continuous fractional quantification of cholesterol in high density lipoproteins and cholesterol in low density lipoproteins; a reagent kit to be used; a method for continuous fractional quantification of cholesterol in high density lipoproteins and total cholesterol; and a quantification reagent kit to be used.
U.S. Pat. No. 5,705,515 to Fisher; Michael H. et al.; U.S. Pat. No. 6,043,253 to Brockunier; Linda et al.; U.S. Pat. No. 6,034,106 to Biftu; Tesfaye et al.; and U.S. Pat. No. 6,011,048 to Mathvink; Robert J. et al. (Merck) describes substituted sulfonamides, fused piperidine substituted arylsulfonamides; oxadiazole substituted benzenesulfonamides and thiazole substituted benzenesulfonamides, respectively, as β3 adrenergic receptor agonists with very little β1 and β2 adrenergic receptor activity as such the compounds are capable of increasing lipolysis and energy expenditure in A cells. The compounds thus have potent activity in the treatment of Type II diabetes and obesity. The compounds can also be used to lower triglyceride levels and cholesterol levels or raise high density lipoprotein levels or to decrease gut motility. In addition, the compounds can be used to reduced neurogenic inflammation or as antidepressant agents. Compositions and methods for the use of the compounds in the treatment of diabetes and obesity and for lowering triglyceride levels and cholesterol levels or raising high density lipoprotein levels or for decreasing gut motility are also disclosed.
U.S. Pat. No. 5,773,304 to Hino discloses a method for quantitatively determining cholesterol in high density lipoproteins, in which, prior to the determination of cholesterol by an enzymatic method, a surfactant and a substance which forms a complex with lipoproteins other than high density lipoproteins are added to a sample containing lipoproteins. The method does not require any pretreatments such as centrifugal separation. With a simple operation, cholesterol in HDLs can be measured effectively. Also, this method can be adopted in a variety of automated analyzers, and thus is very useful in the field of clinical assays.
U.S. Pat. No. 5,707,822 to Fischettiet al. discloses methods and compositions for cloning and expression of serum opacity factor of Streptococcus pyogenes genes. The portion produced by the recombinant DNA techniques may be employed in qualitative and quantitative testing for high density lipoprotein, as a fibronectin binding factor and for the regulation of high density lipoprotein in a mammal. The gene may further be employed as a molecular probe for accurate identification of opacity factors from various strains of Streptococcus pyogenes.
U.S. Pat. No. 5,120,766 to Holloway et al. describes the use of 2-(phenoxypropanolamino)ethoxyphenoxyacetic acid derivatives or a pharmaceutically acceptable salt thereof, in lowering triglyceride and/or cholesterol levels and/or increasing high density lipoprotein levels. These compounds are used in treating hypertriglycerdaemia, hyper-cholesterolaemia, conditions of low HDL (high density lipoprotein) levels and atherosclerotic disease.
U.S. Pat. No. 6,193,967 to Morganelli discloses bispecific molecules which react both with an Fcγ receptor for immunoglobulin G (IgG) of human effector cells and with either human low density lipoprotein (LDL), or fragment thereof, or human high density lipoprotein (HDL), or a fragment thereof. The bispecific molecules bind to a Fcγ receptor without being blocked by the binding of IgG to the same receptor. The bispecific molecules having a binding specificity for human LDL are useful for targeting human effector cells for degradation of LDL in vivo. The bispecific molecules of the present invention which have a binding specificity for human HDL are useful for targeting human HDL to human effector cells such that the HDL takes up cholesterol from the effector cells. Also disclosed are methods of treating atherosclerosis using these bispecific molecules.
U.S. Pat. No. 6,162,607 to Miki et al. provides a method and a kit for measuring the amount of an objective constituent contained in a specific lipoprotein in a biological sample such as serum and plasma, specifically for measuring the amount of cholesterol contained in high density lipoprotein, which can be applicable to clinical tests.
U.S. Pat. No. 6,133,241 Bok et al. discloses a method for increasing the plasma high density lipoprotein (HDL) level in a mammal comprises administering a bioflavonoid or its derivative.
U.S. Pat. No. 6,090,836 to Adams et al. discloses acetylphenols which are useful as antiobesity and antidiabetic compounds. Compositions and methods for the use of the compounds in the treatment of diabetes and obesity and for lowering or modulating triglyceride levels and cholesterol levels or raising high density lipoprotein levels or for increasing gut motility or for treating atherosclerosis.
U.S. Pat. No. 5,939,435 to Babiak use of 2-substituted-l-acyl-1,2-dihydroquinoline derivatives to increase high density lipoprotein cholesterol (HDL-C) concentration and as therapeutic compositions for treating atherosclerotic conditions such as dyslipoproteinamias and coronary heart disease.
U.S. Pat. No. 5,932,536 to Wright et al. describe compositions and methods for neutralizing lipopolysaccharide, and treatment of gram-negative sepsis based therein. Accordingly, the invention is directed to a composition of homogeneous particles comprising phospholipids and a lipid exchange protein, such as phospholipid transfer protein or LPS binding protein. The lipid exchange protein is characterized by being capable of facilitating an exchange protein of lipopolysaccharide into the particles. In a specific embodiment, exemplified herein, the lipid particles are high density lipoprotein particles comprising apolipoprotein A-I (apo A-I), a phospholipid, and cholesterol or a lipid bilayer binding derivative thereof. In a specific example, the phospholipid is phosphatidylcholine (PC). In a specific example, the ratio of phosphatidylcholine:cholesterol:apolipoprotein A-I is approximately 80:4:1. The levels of LPS exchange protein activity in a sample from a patient provides a diagnostic, monitoring, or prognostic indicator for a subject with endotoxemia, gram-negative sepsis, or septic shock.
U.S. Pat. No. 4,215,993 to James L. Sanders describes a method for isolating high density lipoproteins from low density lipoproteins in human serum together with a quantitative determination of high density lipoprotein cholesterol. Precipitation of low density lipoproteins is accomplished by a precipitating reagent without the addition of metal ions into the sample. The precipitating reagent lowers the pH of the human serum approximately to the isoelectric point of the low density lipoproteins through the use of an organic buffer. The precipitating reagent also contains a polyanion and neutral polymer. The preferred composition of the precipitating reagent contains about 0.4% phosphotungstic acid by weight thereof, about 2.5% of polyethylene glycol by weight thereof and 2-i-morpholino) ethane sulfonic acid as the buffer present in a concentration of from about 0.2 molar to about 0.5 molar. According to the method provided, the precipitating reagent is added to the human serum sample thereby causing the low density lipoproteins to form a precipitate, leaving the high density lipoproteins in the resulting supernatant liquid. The supernatant is separated from the precipitate and a cholesterol assay reagent is added to the supernatant. The cholesterol assay reagent reacts with the high density lipoprotein to produce a compound that absorbs radiation at a specific wavelength. The amount of high density lipoprotein cholesterol present in the human serum sample is then determined by comparing the absorbance of a sample with the absorbance of a known standard.
U.S. Pat. No. 5,262,439 to Parthasarathy discloses analogs of probucol with increased water solubility in which one or both of the hydroxyl groups are replaced with ester groups that increase the water solubility of the compound. In one embodiment, the derivative is selected from the group consisting of a mono- or di-probucol ester of succinic acid, glutaric acid, adipic acid, seberic acid, sebacic acid, azelaic acid or maleic acid. In another embodiment, the probucol derivative is a mono- or di-ester in which the ester contains an alkyl or alkenyl group that contains a functionality selected from the group consisting of a carboxylic acid group, amine group, salt of an amine group, amide groups, amide groups and aldehyde groups.
WO 98/09773 filed by AtheroGenics, Inc. discloses that monoesters of probucol, and in particular, the monosuccinic acid ester of probucol, are effective in simultaneously reducing LDLc, and inhibiting the expression of VCAM-1. These compounds are useful as composite cardiovascular agents. Since the compounds exhibits three important vascular protecting activities simultaneously, the patient can take one drug instead of multiple drugs to achieve the desired therapeutic effect.
De Meglio et al., have described several ethers of symmetrical molecules for the treatment of hyperlipidemia. These molecules contain two phenyl rings attached to each other through a —S—C(CH3)2—S— bridge. In contrast to probucol, the phenyl groups do not have t-butyl as substituents. (De Meglio et al., New Derivatives of Clofibrate and probucol: Preliminary Studies of Hypolipemic Activity; Farmaco, Ed. Sci (1985), 40 (11), 833-44).
WO 00/26184 discloses a large genus of compounds with a general formula of phenyl-S-alkylene-S-phenyl, in which one or both phenyl rings can be substituted at any position. These compounds were disclosed as lubricants.
A series of French patents disclose that certain probucol ester derivatives are hypocholesterolemic and hypolipemic agents: Fr 2168137 (bis 4-hydroxyphenylthioalkane esters); Fr 2140771 (tetralinyl phenoxy alkanoic esters of probucol); Fr 2140769 (benzofuryloxyalkanoic acid derivatives of probucol); Fr 2134810 (bis-(3-alkyl-5-t-alkyl-4-thiazole-5-carboxy)phenylthio)alkanes; FR 2133024 (bis-(4-nicoinoyloxyphenythio)propanes; and Fr 2130975 (bis(4-(phenoxyalkanoyloxy)-phenylthio)alkanes).
U.S. Pat. No. 5,155,250 discloses that 2,6-dialkyl-4-silylphenols are antiatherosclerotic agents. The same compounds are disclosed as serum cholesterol lowering agents in PCT Publication No. WO 95/15760, published on Jun. 15, 1995. U.S. Pat. No. 5,608,095 discloses that alkylated-4-silyl-phenols inhibit the peroxidation of LDL, lower plasma cholesterol, and inhibit the expression of VCAM-1, and thus are useful in the treatment of atherosclerosis.
U.S. Pat. No. 5,783,600 discloses that dialkyl ethers lower Lp(a) and triglycerides and elevate HDL-cholesterol and are useful in the treatment of vascular diseases.
A series of European patent applications of Shionogi Seiyaku Kabushiki Kaisha disclose phenolic thioethers for use in treating arteriosclerosis. European Patent Application No. 348 203 discloses phenolic thioethers which inhibit the denaturation of LDL and the incorporation of LDL by macrophages. The compounds are useful as anti-arteriosclerosis agents. Hydroxamic acid derivatives of these compounds are disclosed in European Patent Application No. 405 788 and are useful for the treatment of arteriosclerosis, ulcer, inflammation and allergy. Carbamoyl and cyano derivatives of the phenolic thioethers are disclosed in U.S. Pat. No. 4,954,514 to Kita, et al.
U.S. Pat. No. 4,752,616 to Hall, et al., discloses arylthioalkylphenylcarboxylic acids for the treatment of thrombotic disease. The compounds disclosed are useful as platelet aggregation inhibitors for the treatment of coronary or cerebral thromboses and the inhibition of bronchoconstriction, among others.
A series of patents to Adir et Compagnie disclose substituted phenoxyisobutyric acids and esters useful as antioxidants and hypolipaemic agents. This series includes U.S. Pat. Nos. 5,206,247 and 5,627,205 to Regnier, et al. (which corresponds to European Patent Application No. 621 255) and European Patent Application No. 763 527.
WO 97/15546 to Nippon Shinyaku Co. Ltd. discloses carboxylic acid derivatives for the treatment of arterial sclerosis, ischemic heart diseases, cerebral infarction and post PTCA restenosis.
The Dow Chemical Company is the assignee of patents to hypolipidemic 2-(3,5-di-tert-butyl-4-hydroxyphenyl)thio carboxamides. For example, U.S. Pat. Nos. 4,029,812, 4,076,841 and 4,078,084 to Wagner, et al., disclose these compounds for reducing blood serum lipids, especially cholesterol and triglyceride levels.
WO 98/51662 filed by AtheroGenics, Inc. discloses therapeutic agents for the treatment of diseases, including cardiovascular diseases, which are mediated by VCAM-1, including compounds of formula I below. The PCT application also describes a method of inhibiting the peroxidation of LDL lipid, as well as lowering LDL lipids, in a patient in need thereof by administering an effective amount of the defined compound. The application does not address how to increase high density lipoprotein cholesterol levels, or how to improve the functionality of circulating high density lipoprotein. wherein                Ra, Rb, Rd, and Rd are independently any group that does not otherwise adversely affect the desired properties of the molecule, including hydrogen, straight chained, branched, or cyclic alkyl which may be substituted, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkaryl, substituted alkaryl, aralkyl or substituted aralkyl; substituents on the Ra, Rb, Rc and Rd groups are selected from the group consisting of hydrogen, halogen, alkyl, nitro, amino, haloalkyl, alkylamino, dialkylamino, acyl, and acyloxy;        Z is selected from the group consisting of hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, aralkyl, alkaryl, heteroaryl, heteroaralkyl, a carbohydrate group, —(CH2)—Re, —C(O)—Rg, and —C(O)—(CH2)n—Rh, wherein (a) when each of Ra, Rb, Rd, and Rd are t-butyl, Z cannot be hydrogen and (b) when each of Ra, Rb, Rd, and Rd are t-butyl, Z cannot be the residue of succinic acid;        Re is selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkyloxy, alkoxyalkyl, substituted alkoxyalkyl, NH2, NHR, NR2, mono- or polyhydroxy-substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyloxy, substituted acyloxy, COOH, COOR, —CH(OH)Rk, hydroxy, C(O)NH2, C(O)NHR, C(O)NR2;        Rg is selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkyloxy, alkoxyalkyl, substituted alkoxyalkyl, NH2, N-HR, NR2, mono- or polyhydroxy-substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl;        Rh is selected from the group consisting of alkyl substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkyloxy, alkoxyalkyl, substituted alkoxyalkyl, NH2, NHR, NR2, mono- or polyhydroxy-substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyloxy, substituted acyloxy, COOH, COOR, —CH(OH)Rk, hydroxy, O-phosphate, C(O)NH2, C(O)NHR, C(O)NR2 and pharmaceutically acceptable salts thereof.        
PCT/US01/09049, filed Mar. 21, 2001 by AtheroGenics, Inc., discloses a subclass of thioethers of formula (II) below that are useful in treating diseases mediated by VCAM-1, inflammatory disorders, cardiovascular diseases, occular diseases, automimmune diseases, neurological diseases, cancer, hypercholesterolemia and/or hyperlipidemia. The application does not address how to increase high density lipoprotein cholesterol levels, or how to improve the functionality of circulating high density lipoprotein. wherein                a) Ra, Rb, Rc, and Rd are independently any group that does not adversely affect the desired properties of the molecule, including hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkaryl, substituted alkaryl, aralkyl, or substituted aralkyl; and        Z is (i) a substituted or unsubstituted carbohydrate, (ii) a substituted or unsubstituted alditol, (iii) C1-10alkyl or substituted C1-10alkyl, terminated by sulfonic acid, (iv) C1-10alkyl or substituted C1-10alkyl, terminated by phosphonic acid, (v) substituted or unsubstituted C1-10alkyl-O—C(O)—C1-10alkyl, (vi) straight chained polyhydroxylated C3-10 alkyl; (vii) —(CR2)1-6—COOH, wherein R is independently hydrogen, halo, amino, or hydroxy, and wherein at least one of the R substituents is not hydrogen; or (viii) —(CR2)1-6—X, wherein X is aryl, heteroaryl, or heterocycle, and R is independently hydrogen, halo, amino, or hydroxy.        
Since cardiovascular disease is the leading cause of death in North America and in other industrialized nations, there is a need to provide new therapies for its treatment, especially treatments that work through a mechanism different from the current drugs and can be used in conjunction with them.
It is an object of the present invention to provide new compounds, compositions and methods that are useful as HDLc elevating agents.
It is another object of the present invention to provide methods for identifying compounds that elevate plasma HDL cholesterol levels and improve the functionality of HDL.
It is another object of the present invention to provide methods for identifying compounds that increase selective uptake of cholesteryl esters.
It is another object of the present invention to provide a new method to improve the HDL/total cholesterol ratio by elevating HDLc levels.
It is another object of the present invention to provide an assay to assess the effectiveness of the new method to increase HDL cholesterol and HDL functionality.
It is another object of the present invention to provide assays to assess the effectiveness of the new method to increase HDL holoprotein levels by decreasing the internalization and degradation of HDL holoproteins.
It is still another object of the present invention to provide new compounds and compositions that increase the selective uptake of cholesteryl ester.